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#ThursdaySleepExplainer #5:
How light can influence your sleep:
Spoiler: I'm not going to tell you to put away your screens in the evening
How much light exposure you get, and WHEN you get it, are possibly the most underrated factors for your sleep health.
Here's why:
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How light can influence your sleep:
Spoiler: I'm not going to tell you to put away your screens in the evening
How much light exposure you get, and WHEN you get it, are possibly the most underrated factors for your sleep health.
Here's why:
1/7
Circadian rhythms 101:
- We all have billions of "clocks" in our cells, organs, and bio systems
- The central clock is the tiny but important suprachiasmatic nucleus (SCN) in the
- How well the SCN works affects all aspects of your health (bc your body likes rhythms)
2/7
- We all have billions of "clocks" in our cells, organs, and bio systems
- The central clock is the tiny but important suprachiasmatic nucleus (SCN) in the
- How well the SCN works affects all aspects of your health (bc your body likes rhythms)
2/7
Your brain's central clock (the SCN), like an orchestra's conductor, keeps time for all your bio clocks, including the sleep-wake system. If it does its job well, you are alert during the day and sleep well at night.
But how does the SCN know what time it is?
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But how does the SCN know what time it is?
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The SCN figures out what time it is from the cues you give it.
The strongest cue you can give is light.
That's bc you have special cells in your retina (inner back wall of the eyeball
) that detect light and tell the SCN just how much light there is at all times. So...
4/7
The strongest cue you can give is light.
That's bc you have special cells in your retina (inner back wall of the eyeball
) that detect light and tell the SCN just how much light there is at all times. So...4/7
Getting bright, broad spectrum light from the sun (or short wavelength, aka blue light, from screens) during the day will tell the SCN it's daytime. Getting it during the night will also tell the SCN it's daytime.
This confuses the SCN and is not good for sleep.
CAVEAT...
5/7
This confuses the SCN and is not good for sleep.
CAVEAT...
5/7
If you sit in a very dim room all day, even a little bit of light (say, from a phone screen) in the evening will confuse your SCN.
However, if you spend even 1 daytime hour outside (even if it's overcast), the same evening phone screen will not matter.
It's all relative!
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However, if you spend even 1 daytime hour outside (even if it's overcast), the same evening phone screen will not matter.
It's all relative!
6/7
Take home:
- Your SCN (central bio clock in the) loves consistent timing + clear night vs day differences in light levels.
- If the SCN is happy, you're much likelier to sleep and wake well
- So, get lots of
during the day
- ...and keep your rise time consistent
7/7
- Your SCN (central bio clock in the
) loves consistent timing + clear night vs day differences in light levels. - If the SCN is happy, you're much likelier to sleep and wake well
- So, get lots of
during the day- ...and keep your rise time consistent
7/7
References:
https://pubmed.ncbi.nlm.nih.gov/29934559/
https://pubmed.ncbi.nlm.nih.gov/15240654/
Jamie Zeitzer, PhD (8/12/2020): "Manipulating circadian rhythms" - SRS Trainee Symposia Series 2020
https://pubmed.ncbi.nlm.nih.gov/29934559/
https://pubmed.ncbi.nlm.nih.gov/15240654/
Jamie Zeitzer, PhD (8/12/2020): "Manipulating circadian rhythms" - SRS Trainee Symposia Series 2020
Oops, my bad. This was #ThursdaySleepExplainer #4, not #5! Losing my sense of time over here...
What even is time? Does it exist?
What even is time? Does it exist?
